The development means that human therapeutic cloning is a step closer to reality, says Australian stem cell expert Professor Alan Trounson, who was at the meeting.

Scientists can't properly judge the work until it has been published, says Trounson, but he is "cautiously optimistic" about its potential.

"It's exciting, because it looks terrific," says Trounson, who is director of the Monash Immunology and Stem Cell Laboratories at Monash University in Melbourne.

Until now, scientists have been able to clone other animal species, such as Dolly the sheep, but have failed at all attempts to do the same for primates, our closest animal cousins.

Mitalipov himself would not speak to the media, but his conference presentation showed that his group had successfully created a cloned embryo from a rhesus monkey.

The team inserted the nucleus from an adult monkey skin cell into a monkey egg that had its own nucleus removed - a process known as somatic cell nuclear transfer (SCNT).

By encouraging that cells like this to divide, the scientists were able to create early-stage embryos, called blastocysts, from which they could extract stem cells.

They were then able to use those cells to create two self-replicating stem cell lines.

Trounson says Australian scientists will be interested in the news, particularly since they have recently been granted legal right to use SCNT to produce stem cells.

"This will give us some confidence to proceed, now that the law is enabling in Australia," he says.

Scientists lobby for human-animal embryos

In related news this week, the UK Academy of Medical Sciences says scientists in the UK and the US should maintain the legal right to create human-animal embryos using SCNT.

Australian laws do not permit this option for generating stem cells.

The UK academy said the embryos should never be implanted into either a woman or an animal.

Researchers routinely make chimeras - animals that contain the genetic material from more than one individual. These include animals that carry human genes, most commonly mice engineered with human genes that are used to study disease.

"We found no current scientific reasons to generate 'true' hybrid embryos by mixing human and animal gametes [eggs and sperm]," said Professor Martin Bobrow of Britain's Wellcome Trust, who chaired the panel making the recommendations.

"However, given the speed of this field of research, the working group could not rule out the emergence of scientifically valid reasons in the future."